1. Field of the Invention
The present invention relates to fluorine-containing ethylene copolymer compositions having grafted fluorine-containing functionality. The present invention also relates to polymer blends obtained from fluorine-containing ethylene copolymers described herein. The present invention also relates to a process for preparing the fluorine-containing ethylene copolymers of the present invention.
2. Discussion of the Related Art
Fluoropolymer compositions are widely used for surface modification, as agents to impart desirable surface properties to various types of surfaces. For example, fluoropolymer compositions can impart or enhance the water and oil repellency of certain surfaces, including fabrics and upholstery. However, surface treatment using fluoropolymers can involve complex processing steps to ensure that the fluoropolymer is applied and bonded to the surface being treated. The process can be difficult and expensive. Organic solvent vapors can be released to the atmosphere during the processing. Surface treatment can involve high temperature curing of the fluoropolymer to the substrate surface.
To impart water and oil repellency, fluorochemicals or fluoropolymers can be dissolved or dispersed either in organic solvents or in water. For example, mixtures of fluorinated copolymers, mainly comprising perfluoroalkyl methacrylate, and vinyl copolymers are disclosed in U.S. Pat. No. 3,277,039. U.S. Pat. No. 2,803,615 discloses acrylate/methacrylate esters of N-alkyl or N-alkanol perfluoroalkanesulfonamides used to impart grease and oil repellency. Fluorochemical compositions for treating textile fibers and fabrics comprising an aqueous solution or dispersion of a fluorochemical acrylate and a polyalkoxylated polyurethane having pendant perfluoroalkyl groups is described in U.S. Pat. No. 5,350,557. U.S. Pat. No. 5,536,304 describes a composition for imparting water and oil repellency comprising a fluoroaliphatic radical containing agent, and a cyclic carboxylic acid anhydride-containing polysiloxane.
Fluorochemicals can be melt-blended with thermoplastic polymers, and thereby impart water and oil repellency to the polymer by migrating to the polymer surface as described in, for example, U.S. Pat. No. 5,025,052, wherein the preparation of fluoroaliphatic radical-containing oxazolidinone compositions for blending with thermoplastic polymers is described. U.S. Pat. No. 5,380,778 describes thermoplastic compositions comprising fluoroaliphatic radical containing aminoalcohols and a thermoplastic synthetic organic polymer.
Ethylene copolymers are useful polymeric materials in many applications. Ethylene copolymers can find use in applications such as packaging, laminate films, and adhesives for example. Conventional polyolefins such as polypropylene, polyethylene, and conventional ethylene copolymers have high surface tension relative to fluoropolymers such as polytetrafluoroethylene, for example. As a result, for applications wherein water and oil repellency is important, articles made from polyolefins must be treated to attain a satisfactory level of repellency. However, due to their relatively low melting point and lack of reactive functional groups, treatment of polyolefins with fluorochemicals or fluoropolymers is, in general, much more difficult than treating other thermoplastic polymers.
Copolymers of ethylene and fluorine-containing monomers are known. For example, Tefzel®, manufactured by E.I DuPont de Nemours and Company, is a copolymer of ethylene and tetrafluoroethylene. Copolymers of this type are very different from conventional polyethylene copolymers in many aspects. For example, fluorine-containing ethylene copolymers are typically melt-processable only at much higher temperature than conventional ethylene polymers and ethylene copolymers, and the properties of fluorine-containing ethylene copolymers differ form conventional ethylene copolymers. Copolymers of this type are not amenable to manufacture or processing under the type of conditions used to manufacture and process conventional ethylene copolymers. Ethylene/fluoromonomer copolymers of this type are not compatible in systems that currently use polyethylene copolymers. For example, known conventional ethylene/tetrafluoroethylene copolymers have no adhesion to polyethylene.
It would be desirable to have a fluorine-containing ethylene copolymer that can be processed in the same way as conventional ethylene copolymers. It would be desirable to have a melt-processable fluorine-containing ethylene copolymer. It would be desirable to have a fluorine-containing ethylene copolymer that has a low surface tension. It would be desirable to have a fluorine-containing ethylene copolymer that can be compatible with, or used in place of conventional ethylene copolymers.